Electrically conductive polyaniline

ABSTRACT

Polyanilines are provided that are soluble and that form crystaline solids upon precipitation. The solid polyanilines are electrically conductive, soluble, and can be fabricated into various shaped articles for use in, for example, batteries, electrodes, photovoltaic cells, semiconductor devices and the like.

ACKNOWLEDGMENT OF GOVERNMENT SUPPORT

This invention was made with U.S. Government support under Grant No.DMR-87-03399 awarded by the National Science Foundation. The U.S.Government has certain rights in this invention.

FIELD OF THE INVENTION

This invention relates generally to conducting polymers, and moreparticularly relates to electrically conductive, shaped articles such asfibers, tapes, rods and films of polyaniline as processed and fabricatedfrom solutions in certain strong acids.

BACKGROUND OF THE INVENTION

Polyaniline has emerged as one of the more promising conductingpolymers, because of its excellent chemical stability combined withrespectable levels of electrical conductivity of the doped or protonatedmaterial. Processing of polyaniline into useful objects and devices,however, has been problematic. Melt processing is not possible, sincethe polymer decomposes at temperatures below a softening or meltingpoint. In addition, major difficulties have been encountered in attemptsto dissolve the material.

Conflicting reports exist on the solubility of polyaniline, withcontradictory views advanced as early as 1910. Willstatter and Dorogireported that an oligomeric (eight-monomer chain compound) aniline waslargely insoluble. Willstatter et al. (1909) Ber 42:2147; id. at 4118.Green and Woodhead repeated their experiments and claimed solubility ofthis nonpolymeric material in 80% acetic acid, 60% formic acid, pyridineand concentrated sulfuric acid. Green et al. (1910) J. Chem. Soc.97:2388; Green et al. (1912) J. Chem. Soc. 101:1117. In recent years,Angelopoulos and coworkers and Wang et al. reported only partialsolubility of polyaniline, in its emeraldine base form, inN-methylpyrrolidone (NMP), dimethylformamide (DMF), tetrahydrofuran(THF), benzene and chloroform. Angelopoulos et al. (1987) Synth. Met.21:21); Wang et al. (1986) Synth. Met. 16:99. As a result, it has becomecommon, laborious practice to "remove insoluble material", and use thesoluble, probably oligomeric, polyaniline fraction for the preparationof films. Angelopoulos et al. (1987) Synth. Met. 21:21. Such cast filmsare predominantly amorphous, much like the as-synthesized material.Annis et al. (1986) Synth. Met. 22:191; Andreatta et al. (to bepublished). More recently, Watanabe and coworkers claimed totalinsolubility of the emeraldine salt of polyaniline in any solvent.Watanabe et al. (1987) Chem. Commun. 3.

Trevoy, U.S. Pat. No. 4,025,342, reports that emeraldine sulfate is aninsoluble microcrystalline powder, thus lacking utility in practicalconducting coatings. Trevoy proposes to solve this problem by combiningshort oligomers of aniline salts with other, more easily processedpolymers. Jasne, U.S. Pat. No. 4,731,408, also recognized the need forimproved processability of conducting polymers such as polyaniline,noting particularly insolubility as a problem. Jasne proposes preparingpolyaniline by polymerizing the monomer in a latex dispersion whichserves as a counter ion, the latex comprising 50-97% by weight of theresulting film. Yang et al., U.S. Pat. No. 4,586,792, also recognizesthe insolubility of polyaniline.

Routes towards soluble polyaniline include the preparation of graft andco-polymers, and polyaniline derivatives. Li et al. (1987) Synth. Met.20:141; Li et al. (1988) Synth. Met. (in press); Wang et al. (1986)Synth. Met. 16:99; Ray et al. (19880 Synth. Met. (in press).Unfortunately, these species invariably show significantly reducedconductivities in comparison with the (unmodified) homopolymer.

Until now, this polyaniline generally has been categorized asintractable and amorphous. Polyaniline articles, therefore, aretypically fabricated through elaborate compaction techniques, yieldingrelatively poor mechanical coherence, frequently withpoly(tetrafluoroethylene) binder material. Thus, the ability tofabricate high quality, crystalline polyaniline into shaped articlessuch as fibers, films and the like remains seriously limited, despitenearly eighty years of research.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to overcome theaforementioned disadvantages of the prior art and to provide shapedarticles, oriented fibers, tapes and the like of a crystallinepolyaniline by processing from solution.

It is another object of the invention to provide shaped articles,oriented fibers, tapes and the like from composites or polyblends of acrystalline polyaniline and other polymers (for example polyamides,aromatic polyamides (aramids), etc., etc.) that co-dissolve withpolyaniline in acids.

A further object of the invention is to apply the above objects topolyanilines generally, as well as polyaniline per se in its emeraldinesalt, emeraldine base, or leucoemeraldine base forms.

These and other objects can be achieved by one or more of the followingembodiments of the invention.

In one embodiment, the present invention is directed to a solidcomposition comprising a crystalline polyaniline. In a preferredembodiment, the solid polyaniline is completely soluble.

In another embodiment, the invention is directed to a liquid compositioncomprising in solution (i) a polyaniline having a minimum molecularweight of about 5000, and (ii) an acid capable of dissolving saidpolyaniline.

In a further embodiment, the invention is directed to a method offabricating a shaped article comprising: (a) providing a liquid polymercomposition containing a polyaniline dissolved in an acid; and (b)subjecting said liquid polymer composition to a shaping step selectedfrom the group consisting of spinning, casting or extrusion, wherebysaid polyaniline is precipitated to a solid in a crystalline form.

Additional embodiments, objects, advantages and novel features of theinvention are set forth in part in the description which follows, orbecome apparent to those of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the wide-angle X-ray diffraction pattern of a polyanilinefilm, precipitated in H₂ O from a 15% w/w solution H₂ SO₄ .

FIG. 2 shows the optical micrograph (crossed polarizers) of polyanilinespherulitic structures grown from a 15% solution in H by exposure toair.

FIG. 3 WAXS-pattern of polyaniline showing fiber orientation; the fiberaxis is vertical.

DETAILED DESCRIPTION OF THE INVENTION

In the general practice of the present invention, shaped articles suchas fibers, tapes, rods and films, comprising a crystalline, arefabricated from a solution of the polymer in an acid. Initially,polyaniline is synthesized by any appropriate procedure. The polymermaterial is then completely dissolved in acid. Subsequently, the polymeris processed from these acid solutions into the desired shaped formsmade of high quality, partially crystalline polyaniline in theemeraldine salt form. If desired, the material making up the shapedarticles can be subsequently deprotonated to high quality partiallycrystalline polyaniline in either the emeraldine base form, or the fullyreduced leucoemeraldine form.

Surprisingly, it has been discovered that, (i) high molecular weightpolyanilines are completely soluble in acids, particularly strong acids,(ii) mechanically coherent articles can be processed from thesesolutions of polyaniline, (iii) the resulting material is partiallycrystalline, (iv) the resulting material can be oriented by processingfrom solution, and (v) the resulting coherent objects are electricallyconductive in the as-processed form without need for further treatment.

While the present invention will be described in more detail below withrespect to polyaniline per se, it is to be understood that theprinciples of the present invention are applicable to substitutedpolyanilines as well as polyaniline derivatives. Thus, as used herein, athe polyaniline class (i.e., including substituted or derivative forms)will be referred to collectively as "polyanilines", and members of theclass will be referred to individually as "a polyaniline". Examples ofpolyanalines are those made from monomers having the followingstructure: ##STR1## wherein R₁ can be H or alkyl, preferably H or C₁ -C₅alkyls; and R₂ to R₆ can be any suitable substituent, including alkyl,aralkyl, alkaryl, hydroxy, alkyloxy, halogen, or nitro substituents.Preferred substituents include hydrogen, C₁ -C₁₀ alkyls, methoxy,ethoxy, Cl, F, Br, I, CN, SO₃ H, COOH, COCH₃, NO₂, phenyl, tolyl, andbenzyl. Particularly preferred R₂ -R₆ substituents are hydrogen and C₁-C₅ alkyls.

The invention is also directed to polyanilines in any of their oxidationstates. Thus, with respect to polyaniline, the present inventionincludes the fully reduced leucoemeraldine base, the "half" oxidizedemeraldine base, the fully oxidized pernigraniline base, and theemeraldine salt (e.g., emeraldine hydrochloride). The synthesis ofpolyanilines is well known in the art. See, e.g., Chiang et al. (1986)Synth. Met. 13:193-205; MacDiarmid et al. (1987) Synth. Met. 18:285-290;MacDiarmid et al. (1985) Mol. Cryst. Liq. Cryst. 121:173; U.S. Pat. No.4,520,086; U.S. Pat. No. 4,586,792; U.S. Pat. No. 4,731,408. Theselection of the appropriate synthetic method is within the skill of theart. The resulting product is amorphous, and not crystalline.

Polyaniline prepared by standard methods is then formulated into asolution according to the present invention. The "as synthesized"polyaniline will usually completely dissolve in an acid, particularlystrong acids. Solutions prepared according to the invention willgenerally have at least about 5% (w/w) of polyaniline dissolved in acid.More concentrated solutions, however, can readily be prepared at roomtemperature, e.g., at least about 10% to about 20% (w/w), preferablyabout 15% to about 20% (w/w). Even more concentrated solutions can beprepared at elevated temperatures. These solutions are characterized ascontaining high molecular weight polyaniline, as opposed to only theoligomeric forms dissolved in prior art compositions. For example, themolecular weight of the dissolved polyaniline is usually a minimum ofabout 5000, and preferably about 10,000. More preferred compositionsinclude those where the molecular weight is in the range from about30,000 to about 100,000. The molecular weight of the polyaniline in thesolutions of the present invention can be determined by standardtechniques, such as gel permeation chromatography.

The high molecular weight polyaniline solutions of the present inventioncan also be characterized by viscosity. For example, the roomtemperature inherent viscosity of the dissolved polyanilines of thepresent invention, in concentrated sulfuric acid is usually a minimum ofabout 0.3 dl/g (0.1% w/w polymer). In preferred embodiments, theviscosity is a minimum of about 0.6 dl/g and more preferably a minimumof about 1 dl/g.

Various acids have been found to be suitable solvents for polyaniline.Typically, complete dissolution requires strong acids. Examples ofsuitable acids include H₂ SO₄ (concentrated and fuming), CH₃ SO₃ H,CISO₃ H, CF₃ SO₃ H and HNO₃ (70% or fuming). Generally it is preferredto select acids such as concentrated H₂ SO₄ or CH₃ SO₃ H that completelydissolve the polymer without any degradation. It is within the skill ofthe art based on the present disclosure to screen various acids,particularly strong acids, for their ability to dissolve polyaniline.Degradation of the polymer can be judged from infrared spectra andviscosity.

Solid compositions of the invention comprising polyaniline are preparedby precipitation of polyaniline from the above-described acid solutions.The addition of a liquid in which polyaniline is not soluble to the acidsolutions of the present invention will cause the polyaniline toprecipitate. Various liquids can be used, such as water or organicsolvents miscible in water, such as methanol, ethanol, acetone, aqueoussalt solutions, or even acids in which polyaniline is not soluble. Therate of addition of the non-solvent, temperature, agitation, and thelike will have an effect on the degree of crystallinity of the resultingsolid. However, a crystalline structure is achieved over a wide range ofthese parameters, and the selection of suitable conditions is within theskill of the art in view of the present disclosure. The hydroscopicacid/polyaniline solutions of the present invention can even beprecipitated by merely allowing the absorption of water by thesolutions. Crystalline polymer can also be precipitated by the rapidcontact of the solution with water, such as with spun fibers.

The solid, crystalline polyanilines of the present invention differ fromprior art polyaniline compositions in structure and conductivity. Priorpolyaniline solids were found to be amorphous. In contrast, thepolyaniline solids of the present invention are crystalline, notamorphous, as can be readily shown through X-ray diffraction. Ingeneral, the polyaniline of the present invention are from about 10% toabout 90% crystalline, preferably at least about 25% crystalline, morepreferably at least about 40% crystalline, and most preferably at leastabout 50% crystalline.

Furthermore, the solid polyaniline compositions of the present inventionexhibit substantially greater conductivity than prior art solidpolyanilines. While prior reports for conductivity of polyanilinereported values of no more than about 5 S/cm, the partial crystallinepolyanilines of the present invention exhibit conductivities greaterthan 5 S/cm, preferably greater than 10 S/cm, and more preferably in therange of from about 20 to about 60 S/cm, or more. Another uniqueproperty of some polyanilines of the invention is the ability to becompletely redissolved, including high molecular weight solidpolyaniline, in an acid solution.

Typically, the polyaniline will be produced in an oxidized andprotonated form, such as the emeraldine salt. It is well known how toconvert this salt to other states, such as by compensation to theemeraldine base or by reduction to the leucoemeraldine form. Forexample, the emeraldine salt can be treated with a compensating agent,such as aqueous ammonia. Other suitable compensating agents includedilute aqueous or ethanolic solutions of potassium hydroxide, etc. Toreduce to leucoemeraldine, suitable reducing agents includephenylhydrazine or aqueous solutions of hydrazine.

The invention is also directed to composites or polyblends ofcrystalline polyanilines with other polymers. Examples of such otherpolymers include, but are not limited to, polyamides, aromaticpolyamides (aramids), and the like. Specific examples includepolypara(phenylene terephthalamide) (Kevlar®, DuPont), nylon 6, nylon4.6, nylon 6.6, polyparabenzimide, and sulfonated polystyrene. See,e.g., "Polymer Handbook" (Brandrup & Immergut eds., 2nd ed. 1975). Theprimary consideration in selecting polymers for inclusion in the polymerblends of the present invention is that they be soluble in the acidsolution containing the polyaniline. Typically, polyblends of theinvention will contain a polyaniline in an amount ranging from about 5%to about 95% (w/w) relative to the total amount of polymer. The balancewill be comprised of one or more co-soluble polymers. The inclusion ofadditional polymers in the solid polyaniline articles of the presentinvention can improve the performance characteristics of the solidarticles; e.g., improved tear strength.

The polyaniline or polyaniline blend solutions described above can befabricated into solid articles. Fabrication is accomplished byprecipitating the dissolved polymers as described above. A film, forexample, can be prepared by casting a polyaniline/acid solution onto aglass support, and then contacting the cast solution with water toprecipitate the polyaniline (and other polymers if present) into a film.Fibers can be spun using standard spinning equipment. Other shapes, suchas rods, can be prepared by standard extrusion techniques. The extrudedmaterial (as well as the spun material) is usually contacted immediatelywith a liquid bath, such as water, to fully precipitate the dissolvedpolymer(s).

The solid polyaniline compositions of the present invention have manyapplications. For example, the crystalline polyanilines of the presentinvention can be employed, for example, in electrodes (see, e.g., U.S.Pat. No. 4,461,691); semiconductor devices (see, e.g., U.S. Pat. No.4,025,342); batteries or photovoltaic cells (see, e.g., U.S. Pat. No.4,520,086); and electronic color display devices (see, e.g., U.S. Pat.No. 4,749,260). The disclosures of the foregoing patents areincorporated herein by reference.

The following examples are provided for illustrative purposes only, andare not intended to limit the scope of the present invention, which isdefined in the appended claims.

EXAMPLE 1

Polyaniline was prepared according to the following method. MacDiarmidet al. (1985) Mol. Cryst. Liq. Cryst. 121:173. A solution of 13.3 ml offreshly distilled aniline (Mallinckrodt) and 150 ml of 1.33 M HCl(Fisher) was prepared in an 250 ml Erlenmeyer flask. The flask wasplaced in a cooling bath maintained at -5° C. Polymerization waseffected by addition of an oxidant solution. This oxidant solution wasprepared separately as follows. In a beaker 15.33 g of (NH (Aldrich)were dissolved in 26.7 ml of distilled water. The resulting solution (35ml) was transferred to a 60 cc syringe and was dripped at a rate of 0.58ml/min into the Erlemeyer flask containing the constantly stirredaniline solution. After all oxidant was added (1 hr), the flask wascapped and left stirring overnight. The molar ratio aniline: (NH₄)₂ S₂O₈ was 2:1; the final concentration of HCl in the reaction mixture wasapproximately 1 M.

The (precipitated) polymer powder was recovered, filtered and washedwith distilled water until the pH of washing liquid was 6-7.Subsequently, the polymer was washed with methanol until the liquid wasclear, and then with ethyl ether to eliminate residual water andmethanol. Finally, the polymer was dried overnight in a vacuum oven at60° C. The polyaniline yield was 4.86 g (36.1%).

EXAMPLES 2-4

Example 1 was repeated, but the polymerization temperature was,respectively, 0°, 10° and 30° C.

EXAMPLES 5-7

Examples 1 was repeated, but the oxidant was added over a period of,respectively, 180, 30 and 0.1 min.

EXAMPLES 8-11

Example 1 was repeated, but the molar ratio aniline: (NH₄)₂ S₂ O₈ was,respectively, 8:1, 4:, 1.5:1, and 1:1.

EXAMPLE 12

In agreement with previous findings (Wang et al. (1986) Synth. Met.16:99; Watanabe et al. (1987) Chem. Commun. 3), all "as synthesized"polyanilines (emeraldine salt) were found to be essentially insoluble inDMF and THF. In contrast, all materials synthesized according toExamples 1-11 readily and completely dissolved at room temperature instandard, concentrated (97%) sulfuric acid, to polymer concentrations ashigh as 20% w/w, yielding homogeneous viscous solutions of apurple-black color. At elevated temperatures even higher polyanilineconcentrations were obtained.

EXAMPLE 13

Dissolution of polyaniline in sulfuric acid and precipitation in wateror methanol took place without appreciable degradation or crosslinking.This conclusion was derived from the following experimental results.Polyaniline of example 1 (emeraldine base) was extracted withtetrahydrofuran (THF) to remove (20% w/w) oligomeric material. The solidresidue was then completely dissolved in sulfuric acid and subsequentlyprecipitated in water. Since the precipitated material (aftercompensation to the emeraldine base form) exhibited no significantsolubility in THF, we conclude that dissolution in sulfuric acid did notlead to a significant reduction in chain length. Moreover, it wasobserved that the viscosity of polyaniline/sulfuric acid solutions didnot significantly decrease upon storage at room temperature for 4 days.The polyaniline was found to be repeatedly and completely soluble insulfuric acid; thus, dissolution and precipitation occurred withoutsignificant crosslinking. This finding is in stark contrast to resultsgenerally obtained with polyaniline films cast from N-methylpyrrolidone(NMP). These films were in most cases neither re-soluble in NMP nor insulfuric acid, which is indicative of network formation. Andreatta etal. (to be published).

EXAMPLES 14-30

The inherent viscosities (in dl/g) of the polyanilines of Examples 1-16(base form, made by exposure to aqueous NH₃ and subsequent washing withwater followed

by methanol) were determined at 25° C. in H₂ SO₄ (0.1% w/w polymer),using an Ubbelohde viscometer. The results are presented in Table 1.

                  TABLE 1                                                         ______________________________________                                        Polymerization Temperature (°C.)                                       Time to add                                                                   oxidant (min)                                                                              -5     0          10   30                                        ______________________________________                                          0.1        1.08   0.69       0.72 0.56                                      30           1.55   0.85       0.93 0.71                                      60           1.22   1.01       0.98 0.73                                      180          1.24   1.10       0.90 0.75                                      ______________________________________                                    

The conformation of polyaniline in the liquid state is not established,and, as a result, viscosity data are difficult to interpret. Therefore,we carried out viscosity measurements of samples of the rigid chainpolypara-(phenylene terephthalamide) (Kevlar®, DuPont) and of theflexible nylon-6 under identical conditions. From the comparison withresults obtained with these polymers, and Mark-Houwink relationsreported for these systems (Baird et al. (1978) J. Poly. Sci., Poly.Chem. Ed. 16:61; Kamide et al. (1978) Kobunshi Ronbunsha 35:467), weestimate that the molecular weight of the dissolved polyaniline ofExample 1 is between 12,000 (rigid chain limit) and 40,000 (flexiblechain limit). Extraction of the THF-soluble fraction (about 20% w/w)from the base form of polyaniline leads to a significant increase in theviscosity.

EXAMPLE 31

The material of Example 1 was used to investigate the solubility ofpolyaniline in solvents other than sulfuric acid. The results aresummarized in the following Table 2.

                  TABLE 2                                                         ______________________________________                                        Acid             Solubility                                                   ______________________________________                                        CH.sub.3 SO.sub.3 H                                                                            X                                                            CF.sub.3 SO.sub.3 H                                                                            X                                                            CF.sub.3 COOH    d                                                            formic (88%)     d                                                            polyphosphoric   d                                                            CH.sub.3 COOH (100%)                                                                           O                                                            HCl (36%)        O                                                            HF (49%)         O                                                            CISO.sub.3 H     *                                                            H.sub.2 SO.sub.4 (fuming)                                                                      *                                                            HNO.sub.3 (70%)  **                                                           HNO.sub.3 (fuming)                                                                             **                                                           ______________________________________                                         X  completely dissolved                                                       d  slightly dissolved                                                         O  insoluble                                                                  *dissolved with slight degradation (as indicated by infrared spectrum)        **dissolved with major degradation (as indicated by infrared spectrum)   

EXAMPLE 32

The polyaniline (emeraldine salt) of Example 1 was dissolved inconcentrated sulfuric acid. The polymer concentration was 15% w/w. Theviscous solution was cast into a film, and the polyaniline wasprecipitated in water, to form a coherent film. The recoveredpolyaniline film was of the crystalline form. This is evidenced by thewide-angle X-ray diffraction pattern shown in FIG. 2. The formation ofhighly crystalline polymer has not been previously observed either inas-synthesized material or in polyaniline cast from NMP, which islargely amorphous. Annis et al. (1988) Synth. Met. 22:191; Andreatta etal. (to be published). Slow precipitation of the polymer, by exposingpolyaniline/sulfuric acid solutions to moist air, resulted in the growthof birefringent, well-defined spherulitic structures (FIG. 2) andincreased perfection of the corresponding wide-angle X-ray diffractionpattern. After precipitation, the material can be compensated to thecrystalline emeraldine base form by exposure to aqueous NH₃ solutions(and subsequent washing). Similar results were obtained with a widevariety of liquids other than water, such as e.g. methanol.

EXAMPLE 33

Continuous polyaniline monofilaments were prepared from a 20% w/wsolution of the polymer of Example 1 in 96% H₂ SO₄ using alaboratory-scale spinning device. The solutions were extruded at 60° C.,and dry-jet wet spun into chilled water. The as-spun fibers were washedwith distilled water and dried overnight at 60° C. in a vacuum oven,while kept at constant length. The dried fibers were exceptionallysmooth and had a shiny, metal-like appearance. The diameter was 290 mm.

A wide-angle X-ray diffraction pattern of a polyaniline filament isshown in FIG. 3. The pattern reveals orientation in the as-spun fibersproduced in these experiments.

EXAMPLE 34

The electrical conductivity of the as-spun, dried polyaniline(emeraldine salt) fibers of Example 33 was determined to be in the rangefrom 20-60 S/cm, using the standard four-probe method. This valuesignificantly exceeds the conductivity that is commonly reported forpolyaniline (approx. 5 S/cm). MacDiarmid et al. (1986) Synth. Met.18:285; Wudl et al. (1987) J. Am. Chem. Soc. 109:3677.

EXAMPLE 35

A solution was prepared at room temperature in concentrated sulfuricacid of the polyaniline of Example 1 and the rigid chain moleculepoly-para (phenylene terephthalamide) [Kevlar, Du Pont molecular weightapproximately 40,000]. The ratio of the two polymers by weight was 1:1.The overall polymer concentration was 5% w/w. At elevated temperatures,substantially higher polymer concentrations could be obtained. Thesolution was extruded at room temperature, and dry-jet wet spun intochilled water. The as-spun monofilaments were washed with distilledwater and dried overnight at 60° C. in a vacuum oven, while kept atconstant length. The dried fibers were exceptionally smooth and had ashiny, metal-like appearance. The electrical conductivity of theas-spun, dried polyaniline composite fibers was determined to be 1 S/cm,using the standard four-probe method.

Variations on the above embodiments will be readily apparent to thoseskilled in the art. Thus, the invention is not to be limited thereby andis to be defined according to the following claims.

We claim:
 1. A solid composition comprising an acid soluble,electrically conductive polyaniline having a minimum molecular weight ofat least about 5,000 that is from about 10% to 90% crystalline, saidpolyaniline comprised of monomer units in any of their oxidation stateswhich allow for the composition to be electrically conductive, themonomer units having the structure: ##STR2## wherein R₁ is H or alkyl,and R₂ -R₆ are, independently, H, alkyl, aralalkyl, alkaryl, hydroxy,alkyloxy, halogen or nitro.
 2. The solid composition of claim 1 whereinR₁ -R₆ are H, and the oxidation state of the monomer units of thepolyaniline result in the polyaniline taking a form selected from thegroup consisting of the emeraldine salt form, the emeraldine base form,and leucoemeraldine form.
 3. The solid composition of claim 1 whereinsaid polyaniline has a minimum molecular weight of about 10,000.
 4. Thesolid composition of claim 1 wherein the monomer units consistessentially of aniline and the composition consists essentially ofpolyaniline.
 5. The solid composition of claim 1 wherein the compositionhas a minimum electrical conductivity of about 10 S/cm.
 6. A shapedarticle produced from the composition of claim
 1. 7. The shaped articleof claim 6 which is in the form of a film.
 8. The shaped article ofclaim 6 which is in the form of a fiber.
 9. The shaped article of claim6 which is in the form of a tape.
 10. The shaped article of claim 6which is in the form of a rod.
 11. A shaped article produced from thecomposition of claim
 4. 12. The shaped article of claim 11 which is inthe form of a fiber.
 13. The shaped article of claim 11 which is in theform of a film.
 14. The shaped article of claim 11 which is in the formof a tape.
 15. The shaped article of claim 11 which is in the form of arod.